When imaging a patient's vasculature and when trying to isolate a limited zone of this patient's vasculature, when zooming in a limited zone of this patient's vasculature, what happens is that many vessels are entangled in this limited zone. Therefore, it may not be easy for the radiologist to build in his mind a clear representation of the vasculature architecture in this limited zone or a region of specific interest, including vessel bifurcations or an arteriovenous malformation.
When performing an intervention, the radiologist navigates a tool through the network of vessels with the help of two-dimensional projective images. Vessels may not be visible if no contrast is injected. State-of-the-art interventional systems superimpose over these projective images a two dimensional rendering of the vessel configuration obtained from a prior three dimensional image of the vessels in order to avoid multiple local contrast injections that would image the local configuration of the vessels where the tool is navigated. However, the number of vessels in the three dimensional image and their possible superimposition in the projective images can make difficult the interpretation of the actual local vessel configuration and suggest routes that the tool cannot actually take. Anatomical variations that naturally arise in the population make possible unexpected ambiguous interpretation of the two dimensional rendering.
Similarly, the number of small vessels and their possible relative superimposition in the three dimensional image can make the three dimensional interpretation of a pathology complex. This is particularly the case during the treatment of an arteriovenous malformation. The radiologist would like to identify the vessel(s) which feed(s) the core of the malformation. To try to make this identification, the radiologist visually follows the vessel leading to the pathology using volume rendered two-dimensional views of the volumetric image which are available on the visualization workstation. Each time the feeder, which means the feeding blood vessel, is superimposed to another vessel, the analysis becomes more ambiguous.
The visualization of complex vascular structures in a three dimensional image is a challenging task for the interventional radiologist. Moreover, for an arteriovenous malformation (AVM) treatment, this is even more challenging because the anatomy of such malformations is indeed a complex pattern of abnormally entangled vessels. This is also the case, although to a lesser degree, when analyzing a tumor that has grown a new vessel system to feed itself, as such abnormal vessels are also characteristically disorderly entangled over a feeder vessel that is thus hard to identify.
According to a first prior art, it is known, for radiologists, to use oblique planar representation of the three dimensional image to avoid ambiguities. They may have to go through many oblique planes to follow the vessels on all their respective paths.
According to a second prior art, for example described in U.S. Pat. No. 6,690,816, it is known to make a model of blood propagation in a patient's vasculature. However, this model of blood propagation does not improve in any way the visualization of vascular paths, so it is useless to improve patient's vasculature visualization.